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Krüger J, Lerche H. Retigabine and gabapentin restore channel function and neuronal firing in a cellular model of an epilepsy-associated dominant-negative KCNQ5 variant. Neuropharmacology 2024; 250:109892. [PMID: 38428481 DOI: 10.1016/j.neuropharm.2024.109892] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 01/19/2024] [Accepted: 02/26/2024] [Indexed: 03/03/2024]
Abstract
KCNQ5 encodes the voltage-gated potassium channel KV7.5, a member of the KV7 channel family, which conducts the M-current. This current is a potent regulator of neuronal excitability by regulating membrane potential in the subthreshold range of action potentials and mediating the medium and slow afterhyperpolarization. Recently, we have identified five loss-of-function variants in KCNQ5 in patients with genetic generalized epilepsy. Using the most severe dominant-negative variant (R359C), we set out to investigate pharmacological therapeutic intervention by KV7 channel openers on channel function and neuronal firing. Retigabine and gabapentin increased R359C-derived M-current amplitudes in HEK cells expressing homomeric or heteromeric mutant KV7.5 channels. Retigabine was most effective in restoring K+ currents. Ten μM retigabine was sufficient to reach the level of WT currents without retigabine, whereas 100 μM of gabapentin showed less than half of this effect and application of 50 μM ZnCl2 only significantly increased M-current amplitude in heteromeric channels. Overexpression of KV7.5-WT potently inhibited neuronal firing by increasing the M-current, whereas R359C overexpression had the opposite effect and additionally decreased the medium afterhyperpolarization current. Both aforementioned drugs and Zn2+ reversed the effect of R359C expression by reducing firing to nearly normal levels at high current injections. Our study shows that a dominant-negative variant with a complete loss-of-function in KV7.5 leads to largely increased neuronal firing which may explain a neuronal hyperexcitability in patients. KV7 channel openers, such as retigabine or gabapentin, could be treatment options for patients currently displaying pharmacoresistant epilepsy and carrying loss-of-function variants in KCNQ5.
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Affiliation(s)
- Johanna Krüger
- Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tübingen, Otfried-Müller-Straße 27, 72076, Tübingen, Germany.
| | - Holger Lerche
- Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tübingen, Otfried-Müller-Straße 27, 72076, Tübingen, Germany.
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2
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Zhao T, Wang L, Chen F. Potassium channel-related epilepsy: Pathogenesis and clinical features. Epilepsia Open 2024; 9:891-905. [PMID: 38560778 PMCID: PMC11145612 DOI: 10.1002/epi4.12934] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 03/11/2024] [Accepted: 03/17/2024] [Indexed: 04/04/2024] Open
Abstract
Variants in potassium channel-related genes are one of the most important mechanisms underlying abnormal neuronal excitation and disturbances in the cellular resting membrane potential. These variants can cause different forms of epilepsy, which can seriously affect the physical and mental health of patients, especially those with refractory epilepsy or status epilepticus, which are common among pediatric patients and are potentially life-threatening. Variants in potassium ion channel-related genes have been reported in few studies; however, to our knowledge, no systematic review has been published. This study aimed to summarize the epilepsy phenotypes, functional studies, and pharmacological advances associated with different potassium channel gene variants to assist clinical practitioners and drug development teams to develop evidence-based medicine and guide research strategies. PubMed and Google Scholar were searched for relevant literature on potassium channel-related epilepsy reported in the past 5-10 years. Various common potassium ion channel gene variants can lead to heterogeneous epilepsy phenotypes, and functional effects can result from gene deletions and compound effects. Administration of select anti-seizure medications is the primary treatment for this type of epilepsy. Most patients are refractory to anti-seizure medications, and some novel anti-seizure medications have been found to improve seizures. Use of targeted drugs to correct aberrant channel function based on the type of potassium channel gene variant can be used as an evidence-based pathway to achieve precise and individualized treatment for children with epilepsy. PLAIN LANGUAGE SUMMARY: In this article, the pathogenesis and clinical characteristics of epilepsy caused by different types of potassium channel gene variants are reviewed in the light of the latest research literature at home and abroad, with the expectation of providing a certain theoretical basis for the diagnosis and treatment of children with this type of disease.
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Affiliation(s)
- Tong Zhao
- Hebei Children's HospitalShijiazhuangHebeiChina
| | - Le Wang
- Hebei Children's HospitalShijiazhuangHebeiChina
| | - Fang Chen
- Hebei Children's HospitalShijiazhuangHebeiChina
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3
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Ng ACH, Chahine M, Scantlebury MH, Appendino JP. Channelopathies in epilepsy: an overview of clinical presentations, pathogenic mechanisms, and therapeutic insights. J Neurol 2024; 271:3063-3094. [PMID: 38607431 DOI: 10.1007/s00415-024-12352-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2024] [Revised: 03/24/2024] [Accepted: 03/25/2024] [Indexed: 04/13/2024]
Abstract
Pathogenic variants in genes encoding ion channels are causal for various pediatric and adult neurological conditions. In particular, several epilepsy syndromes have been identified to be caused by specific channelopathies. These encompass a spectrum from self-limited epilepsies to developmental and epileptic encephalopathies spanning genetic and acquired causes. Several of these channelopathies have exquisite responses to specific antiseizure medications (ASMs), while others ASMs may prove ineffective or even worsen seizures. Some channelopathies demonstrate phenotypic pleiotropy and can cause other neurological conditions outside of epilepsy. This review aims to provide a comprehensive exploration of the pathophysiology of seizure generation, ion channels implicated in epilepsy, and several genetic epilepsies due to ion channel dysfunction. We outline the clinical presentation, pathogenesis, and the current state of basic science and clinical research for these channelopathies. In addition, we briefly look at potential precision therapy approaches emerging for these disorders.
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Affiliation(s)
- Andy Cheuk-Him Ng
- Clinical Neuroscience and Pediatric Neurology, Department of Pediatrics, Cumming School of Medicine, Alberta Children's Hospital, University of Calgary, 28 Oki Drive NW, Calgary, AB, T3B 6A8, Canada
- Division of Neurology, Department of Pediatrics, Faculty of Medicine and Dentistry, University of Alberta and Stollery Children's Hospital, Edmonton, AB, Canada
| | - Mohamed Chahine
- Department of Medicine, Faculty of Medicine, Université Laval, Quebec City, QC, Canada
- CERVO, Brain Research Centre, Quebec City, Canada
| | - Morris H Scantlebury
- Clinical Neuroscience and Pediatric Neurology, Department of Pediatrics, Cumming School of Medicine, Alberta Children's Hospital, University of Calgary, 28 Oki Drive NW, Calgary, AB, T3B 6A8, Canada
- Hotchkiss Brain Institute and Alberta Children's Hospital Research Institute, Calgary, Canada
| | - Juan P Appendino
- Clinical Neuroscience and Pediatric Neurology, Department of Pediatrics, Cumming School of Medicine, Alberta Children's Hospital, University of Calgary, 28 Oki Drive NW, Calgary, AB, T3B 6A8, Canada.
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4
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Jan LY, Jan YN. A personal perspective of the voltage-gated potassium channel studies. Nat Struct Mol Biol 2024; 31:580-581. [PMID: 38548955 DOI: 10.1038/s41594-024-01267-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/20/2024]
Affiliation(s)
- Lily Yeh Jan
- Department of Physiology, University of California at San Francisco, San Francisco, CA, USA.
- Howard Hughes Medical Institute, San Francisco, CA, USA.
| | - Yuh Nung Jan
- Department of Physiology, University of California at San Francisco, San Francisco, CA, USA.
- Howard Hughes Medical Institute, San Francisco, CA, USA.
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DeKorver NW, Zhao W, Butler MR, Di Luca DG, Gurnett C, Nascimento F. An adult with KCNA2-related epilepsy and ataxia. Epileptic Disord 2024; 26:264-266. [PMID: 38366944 DOI: 10.1002/epd2.20205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Revised: 01/29/2024] [Accepted: 01/30/2024] [Indexed: 02/19/2024]
Abstract
Content available: Video
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Affiliation(s)
- Nicholas W DeKorver
- Washington University in St Louis Ringgold standard institution - Neurology, St Louis, Missouri, USA
| | - Wei Zhao
- Washington University in St Louis Ringgold standard institution - Neurology, St Louis, Missouri, USA
| | - Michael R Butler
- Washington University in St Louis Ringgold standard institution - Neurology, St Louis, Missouri, USA
| | - Daniel G Di Luca
- Washington University in St Louis Ringgold standard institution - Neurology, St Louis, Missouri, USA
| | - Christina Gurnett
- Washington University in St Louis Ringgold standard institution - Neurology, St Louis, Missouri, USA
| | - Fabio Nascimento
- Washington University in St Louis Ringgold standard institution - Neurology, St Louis, Missouri, USA
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6
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Xie C, Kessi M, Yin F, Peng J. Roles of KCNA2 in Neurological Diseases: from Physiology to Pathology. Mol Neurobiol 2024:10.1007/s12035-024-04120-9. [PMID: 38517617 DOI: 10.1007/s12035-024-04120-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Accepted: 03/10/2024] [Indexed: 03/24/2024]
Abstract
Potassium voltage-gated channel subfamily a member 2 (Kv1.2, encoded by KCNA2) is highly expressed in the central and peripheral nervous systems. Based on the patch clamp studies, gain-of function (GOF), loss-of-function (LOF), and a mixed type (GOF/LOF) variants can cause different conditions/disorders. KCNA2-related neurological diseases include epilepsy, intellectual disability (ID), attention deficit/hyperactive disorder (ADHD), autism spectrum disorder (ASD), pain as well as autoimmune and movement disorders. Currently, the molecular mechanisms for the reported variants in causing diverse disorders are unknown. Consequently, this review brings up to date the related information regarding the structure and function of Kv1.2 channel, expression patterns, neuronal localizations, and tetramerization as well as important cell and animal models. In addition, it provides updates on human genetic variants, genotype-phenotype correlations especially highlighting the deep insight into clinical prognosis of KCNA2-related developmental and epileptic encephalopathy, mechanisms, and the potential treatment targets for all KCNA2-related neurological disorders.
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Affiliation(s)
- Changning Xie
- Department of Pediatrics, Xiangya Hospital, Central South University, Xiangya Road 87, Hunan, Changsha, 410008, China
| | - Miriam Kessi
- Department of Pediatrics, Xiangya Hospital, Central South University, Xiangya Road 87, Hunan, Changsha, 410008, China
| | - Fei Yin
- Department of Pediatrics, Xiangya Hospital, Central South University, Xiangya Road 87, Hunan, Changsha, 410008, China
| | - Jing Peng
- Department of Pediatrics, Xiangya Hospital, Central South University, Xiangya Road 87, Hunan, Changsha, 410008, China.
- Hunan Intellectual and Development Disabilities Research Center, Hunan, Changsha, 410008, China.
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Boßelmann CM, Ivaniuk A, St John M, Taylor SC, Krishnaswamy G, Milinovich A, Leu C, Gupta A, Pestana-Knight EM, Najm I, Lal D. Healthcare utilization and clinical characteristics of genetic epilepsy in electronic health records. Brain Commun 2024; 6:fcae090. [PMID: 38524155 PMCID: PMC10959483 DOI: 10.1093/braincomms/fcae090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2023] [Revised: 02/05/2024] [Accepted: 03/12/2024] [Indexed: 03/26/2024] Open
Abstract
Understanding the clinical characteristics and medical treatment of individuals affected by genetic epilepsies is instrumental in guiding selection for genetic testing, defining the phenotype range of these rare disorders, optimizing patient care pathways and pinpointing unaddressed medical need by quantifying healthcare resource utilization. To date, a matched longitudinal cohort study encompassing the entire spectrum of clinical characteristics and medical treatment from childhood through adolescence has not been performed. We identified individuals with genetic and non-genetic epilepsies and onset at ages 0-5 years by linkage across the Cleveland Clinic Health System. We used natural language processing to extract medical terms and procedures from longitudinal electronic health records and tested for cross-sectional and temporal associations with genetic epilepsy. We implemented a two-stage design: in the discovery cohort, individuals were stratified as being 'likely genetic' or 'non-genetic' by a natural language processing algorithm, and controls did not receive genetic testing. The validation cohort consisted of cases with genetic epilepsy confirmed by manual chart review and an independent set of controls who received negative genetic testing. The discovery and validation cohorts consisted of 503 and 344 individuals with genetic epilepsy and matched controls, respectively. The median age at the first encounter was 0.1 years and 7.9 years at the last encounter, and the mean duration of follow-up was 8.2 years. We extracted 188,295 Unified Medical Language System annotations for statistical analysis across 9659 encounters. Individuals with genetic epilepsy received an earlier epilepsy diagnosis and had more frequent and complex encounters with the healthcare system. Notably, the highest enrichment of encounters compared with the non-genetic groups was found during the transition from paediatric to adult care. Our computational approach could validate established comorbidities of genetic epilepsies, such as behavioural abnormality and intellectual disability. We also revealed novel associations for genitourinary abnormalities (odds ratio 1.91, 95% confidence interval: 1.66-2.20, P = 6.16 × 10-19) linked to a spectrum of underrecognized epilepsy-associated genetic disorders. This case-control study leveraged real-world data to identify novel features associated with the likelihood of a genetic aetiology and quantified the healthcare utilization of genetic epilepsies compared with matched controls. Our results strongly recommend early genetic testing to stratify individuals into specialized care paths, thus improving the clinical management of people with genetic epilepsies.
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Affiliation(s)
- Christian M Boßelmann
- Genomic Medicine Institute, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
- Epilepsy Center, Neurological Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Alina Ivaniuk
- Genomic Medicine Institute, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
- Epilepsy Center, Neurological Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Mark St John
- Genomic Medicine Institute, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
- Epilepsy Center, Neurological Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Sara C Taylor
- Neurological Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | | | - Alex Milinovich
- Department of Quantitative Health Sciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Costin Leu
- Genomic Medicine Institute, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
- Department of Clinical and Experimental Epilepsy, Institute of Neurology, University College London, London, WC1N 3BG, UK
- Department of Neurology, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA
- Center for Neurogenetics, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Ajay Gupta
- Epilepsy Center, Neurological Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | | | - Imad Najm
- Epilepsy Center, Neurological Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Dennis Lal
- Genomic Medicine Institute, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
- Epilepsy Center, Neurological Institute, Cleveland Clinic, Cleveland, OH 44195, USA
- Department of Neurology, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA
- Center for Neurogenetics, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA
- Stanley Center for Psychiatric Research, Broad Institute of Harvard and M.I.T., Cambridge, MA 02142, USA
- Cologne Center for Genomics (CCG), University of Cologne, 50931 Cologne, Germany
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Soldovieri MV, Ambrosino P, Mosca I, Servettini I, Pietrunti F, Belperio G, Syrbe S, Taglialatela M, Lemke JR. De novo variants in KCNA3 cause developmental and epileptic encephalopathy. Ann Neurol 2024; 95:365-376. [PMID: 37964487 DOI: 10.1002/ana.26826] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 10/06/2023] [Accepted: 10/23/2023] [Indexed: 11/16/2023]
Abstract
OBJECTIVE Variants in several potassium channel genes, including KCNA1 and KCNA2, cause Developmental and Epileptic Encephalopathies (DEEs). We investigated whether variants in KCNA3, another mammalian homologue of the Drosophila shaker family and encoding for Kv1.3 subunits, can cause DEE. METHODS Genetic analysis of study individuals was performed by routine exome or genome sequencing, usually of parent-offspring trios. Phenotyping was performed via a standard clinical questionnaire. Currents from wild-type and/or mutant Kv1.3 subunits were investigated by whole-cell patch-clamp upon their heterologous expression. RESULTS Fourteen individuals, each carrying a de novo heterozygous missense variant in KCNA3, were identified. Most (12/14; 86%) had DEE with marked speech delay with or without motor delay, intellectual disability, epilepsy, and autism spectrum disorder. Functional analysis of Kv1.3 channels carrying each variant revealed heterogeneous functional changes, ranging from "pure" loss-of-function (LoF) effects due to faster inactivation kinetics, depolarized voltage-dependence of activation, slower activation kinetics, increased current inactivation, reduced or absent currents with or without dominant-negative effects, to "mixed" loss- and gain-of-function (GoF) effects. Compared to controls, Kv1.3 currents in lymphoblasts from 1 of the proband displayed functional changes similar to those observed upon heterologous expression of channels carrying the same variant. The antidepressant drug fluoxetine inhibited with similar potency the currents from wild-type and 1 of the Kv1.3 GoF variant. INTERPRETATION We describe a novel association of de novo missense variants in KCNA3 with a human DEE, and provide evidence that fluoxetine might represent a potential targeted treatment for individuals carrying variants with significant GoF effects. ANN NEUROL 2024;95:365-376.
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Affiliation(s)
| | - Paolo Ambrosino
- Department of Science and Technology, University of Sannio, Benevento, Italy
| | - Ilaria Mosca
- Department of Medicine and Health Science "V. Tiberio", University of Molise, Campobasso, Italy
| | - Ilenio Servettini
- Department of Medicine and Health Science "V. Tiberio", University of Molise, Campobasso, Italy
| | - Francesca Pietrunti
- Department of Medicine and Health Science "V. Tiberio", University of Molise, Campobasso, Italy
| | - Giorgio Belperio
- Department of Science and Technology, University of Sannio, Benevento, Italy
| | - Steffen Syrbe
- Center for Pediatrics and Adolescent Medicine, Division of Pediatric Epileptology, University Hospital Heidelberg, Heidelberg, Germany
| | - Maurizio Taglialatela
- Department of Neuroscience, Division of Pharmacology, University of Naples "Federico II", Naples, Italy
| | - Johannes R Lemke
- Institute of Human Genetics, University of Leipzig Medical Center, Leipzig, Germany
- Center for Rare Diseases, University of Leipzig Medical Center, Leipzig, Germany
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Khan R, Chaturvedi P, Sahu P, Ludhiadch A, Singh P, Singh G, Munshi A. Role of Potassium Ion Channels in Epilepsy: Focus on Current Therapeutic Strategies. CNS & NEUROLOGICAL DISORDERS DRUG TARGETS 2024; 23:67-87. [PMID: 36578258 DOI: 10.2174/1871527322666221227112621] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Revised: 11/10/2022] [Accepted: 11/12/2022] [Indexed: 12/30/2022]
Abstract
BACKGROUND Epilepsy is one of the prevalent neurological disorders characterized by disrupted synchronization between inhibitory and excitatory neurons. Disturbed membrane potential due to abnormal regulation of neurotransmitters and ion transport across the neural cell membrane significantly contributes to the pathophysiology of epilepsy. Potassium ion channels (KCN) regulate the resting membrane potential and are involved in neuronal excitability. Genetic alterations in the potassium ion channels (KCN) have been reported to result in the enhancement of the release of neurotransmitters, the excitability of neurons, and abnormal rapid firing rate, which lead to epileptic phenotypes, making these ion channels a potential therapeutic target for epilepsy. The aim of this study is to explore the variations reported in different classes of potassium ion channels (KCN) in epilepsy patients, their functional evaluation, and therapeutic strategies to treat epilepsy targeting KCN. METHODOLOGY A review of all the relevant literature was carried out to compile this article. RESULTS A large number of variations have been reported in different genes encoding various classes of KCN. These genetic alterations in KCN have been shown to be responsible for disrupted firing properties of neurons. Antiepileptic drugs (AEDs) are the main therapeutic strategy to treat epilepsy. Some patients do not respond favorably to the AEDs treatment, resulting in pharmacoresistant epilepsy. CONCLUSION Further to address the challenges faced in treating epilepsy, recent approaches like optogenetics, chemogenetics, and genome editing, such as clustered regularly interspaced short palindromic repeats (CRISPR), are emerging as target-specific therapeutic strategies.
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Affiliation(s)
- Rahul Khan
- Department of Human Genetics and Molecular Medicine Central University of Punjab, Bathinda 151401, India
| | - Pragya Chaturvedi
- Department of Human Genetics and Molecular Medicine Central University of Punjab, Bathinda 151401, India
| | - Prachi Sahu
- Department of Human Genetics and Molecular Medicine Central University of Punjab, Bathinda 151401, India
| | - Abhilash Ludhiadch
- Department of Human Genetics and Molecular Medicine Central University of Punjab, Bathinda 151401, India
| | - Paramdeep Singh
- Department of Radiology, All India Institute of Medical Sciences, Bathinda, Punjab, 151001 India
| | - Gagandeep Singh
- Department of Neurology, Dayanand Medical College and Hospital, Ludhiana, Punjab, India
| | - Anjana Munshi
- Department of Human Genetics and Molecular Medicine Central University of Punjab, Bathinda 151401, India
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De Wachter M, Schoonjans AS, Weckhuysen S, Van Schil K, Löfgren A, Meuwissen M, Jansen A, Ceulemans B. From diagnosis to treatment in genetic epilepsies: Implementation of precision medicine in real-world clinical practice. Eur J Paediatr Neurol 2024; 48:46-60. [PMID: 38039826 DOI: 10.1016/j.ejpn.2023.11.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 07/20/2023] [Accepted: 11/11/2023] [Indexed: 12/03/2023]
Abstract
The implementation of whole exome sequencing (WES) has had a major impact on the diagnostic yield of genetic testing in individuals with epilepsy. The identification of a genetic etiology paves the way to precision medicine: an individualized treatment approach, based on the disease pathophysiology. The aim of this retrospective cohort study was to: (1) determine the diagnostic yield of WES in a heterogeneous cohort of individuals with epilepsy referred for genetic testing in a real-world clinical setting, (2) investigate the influence of epilepsy characteristics on the diagnostic yield, (3) determine the theoretical yield of treatment changes based on genetic diagnosis and (4) explore the barriers to implementation of precision medicine. WES was performed in 247 individuals with epilepsy, aged between 7 months and 68 years. In 34/247 (14 %) a (likely) pathogenic variant was identified. In 7/34 (21 %) of these individuals the variant was found using a HPO-based filtering. Diagnostic yield was highest for individuals with an early onset of epilepsy (39 %) or in those with a developmental and epileptic encephalopathy (34 %). Precision medicine was a theoretical possibility in 20/34 (59 %) of the individuals with a (likely) pathogenic variant but implemented in only 11/34 (32 %). The major barrier to implementation of precision treatment was the limited availability or reimbursement of a given drug. These results confirm the potential impact of genetic analysis on treatment choices, but also highlight the hurdles to the implementation of precision medicine. To optimize precision medicine in real-world practice, additional endeavors are needed: unifying definitions of precision medicine, establishment of publicly accessible databases that include data on the functional effect of gene variants, increasing availability and reimbursement of precision therapeutics, and broadening access to innovative clinical trials.
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Affiliation(s)
- Matthias De Wachter
- Department of Pediatric Neurology, Antwerp University Hospital, University of Antwerp, Drie eikenstraat 655, 2650, Edegem, Belgium.
| | - An-Sofie Schoonjans
- Department of Pediatric Neurology, Antwerp University Hospital, University of Antwerp, Drie eikenstraat 655, 2650, Edegem, Belgium
| | - Sarah Weckhuysen
- Department of Neurology, Antwerp University Hospital, University of Antwerp, Drie eikenstraat 655, 2650, Edegem, Belgium; Applied&Translational Neurogenomics Group, VIB-CMN, VIB, UAntwerpen, Universiteitsplein 1, 2610, Wilrijk, Belgium; Translational Neurosciences, University of Antwerp, Universiteitsplein 1, 2610, Wilrijk, Belgium
| | - Kristof Van Schil
- Department of Medical Genetics, Antwerp University Hospital, University of Antwerp, Drie eikenstraat 655, 2650, Edegem, Belgium
| | - Ann Löfgren
- Department of Medical Genetics, Antwerp University Hospital, University of Antwerp, Drie eikenstraat 655, 2650, Edegem, Belgium
| | - Marije Meuwissen
- Department of Medical Genetics, Antwerp University Hospital, University of Antwerp, Drie eikenstraat 655, 2650, Edegem, Belgium
| | - Anna Jansen
- Department of Pediatric Neurology, Antwerp University Hospital, University of Antwerp, Drie eikenstraat 655, 2650, Edegem, Belgium; Translational Neurosciences, University of Antwerp, Universiteitsplein 1, 2610, Wilrijk, Belgium
| | - Berten Ceulemans
- Department of Pediatric Neurology, Antwerp University Hospital, University of Antwerp, Drie eikenstraat 655, 2650, Edegem, Belgium
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Mínguez-Viñas T, Prakash V, Wang K, Lindström SH, Pozzi S, Scott SA, Spiteri E, Stevenson DA, Ashley EA, Gunnarsson C, Pantazis A. Two epilepsy-associated variants in KCNA2 (K V 1.2) at position H310 oppositely affect channel functional expression. J Physiol 2023; 601:5367-5389. [PMID: 37883018 DOI: 10.1113/jp285052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Accepted: 10/11/2023] [Indexed: 10/27/2023] Open
Abstract
Two KCNA2 variants (p.H310Y and p.H310R) were discovered in paediatric patients with epilepsy and developmental delay. KCNA2 encodes KV 1.2-channel subunits, which regulate neuronal excitability. Both gain and loss of KV 1.2 function cause epilepsy, precluding the prediction of variant effects; and while H310 is conserved throughout the KV -channel superfamily, it is largely understudied. We investigated both variants in heterologously expressed, human KV 1.2 channels by immunocytochemistry, electrophysiology and voltage-clamp fluorometry. Despite affecting the same channel, at the same position, and being associated with severe neurological disease, the two variants had diametrically opposite effects on KV 1.2 functional expression. The p.H310Y variant produced 'dual gain of function', increasing both cell-surface trafficking and activity, delaying channel closure. We found that the latter is due to the formation of a hydrogen bond that stabilizes the active state of the voltage-sensor domain. Additionally, H310Y abolished 'ball and chain' inactivation of KV 1.2 by KV β1 subunits, enhancing gain of function. In contrast, p.H310R caused 'dual loss of function', diminishing surface levels by multiple impediments to trafficking and inhibiting voltage-dependent channel opening. We discuss the implications for KV -channel biogenesis and function, an emergent hotspot for disease-associated variants, and mechanisms of epileptogenesis. KEY POINTS: KCNA2 encodes the subunits of KV 1.2 voltage-activated, K+ -selective ion channels, which regulate electrical signalling in neurons. We characterize two KCNA2 variants from patients with developmental delay and epilepsy. Both variants affect position H310, highly conserved in KV channels. The p.H310Y variant caused 'dual gain of function', increasing both KV 1.2-channel activity and the number of KV 1.2 subunits on the cell surface. H310Y abolished 'ball and chain' (N-type) inactivation of KV 1.2 by KV β1 subunits, enhancing the gain-of-function phenotype. The p.H310R variant caused 'dual loss of function', diminishing the presence of KV 1.2 subunits on the cell surface and inhibiting voltage-dependent channel opening. As H310Y stabilizes the voltage-sensor active conformation and abolishes N-type inactivation, it can serve as an investigative tool for functional and pharmacological studies.
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Affiliation(s)
- Teresa Mínguez-Viñas
- Division of Neurobiology, Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Varsha Prakash
- Division of Neurobiology, Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Kaiqian Wang
- Division of Neurobiology, Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Sarah H Lindström
- Division of Neurobiology, Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Serena Pozzi
- Division of Neurobiology, Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Stuart A Scott
- Department of Pathology, Stanford University School of Medicine, Stanford, California, USA
| | - Elizabeth Spiteri
- Department of Pathology, Stanford University School of Medicine, Stanford, California, USA
| | - David A Stevenson
- Division of Medical Genetics, Stanford University, Palo Alto, California, USA
| | - Euan A Ashley
- Division of Medical Genetics, Stanford University, Palo Alto, California, USA
| | - Cecilia Gunnarsson
- Division of Neurobiology, Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
- Department of Clinical Genetics, Linköping University, Linköping, Sweden
- Centre for Rare Diseases in South East Region of Sweden, Linköping University, Linköping, Sweden
| | - Antonios Pantazis
- Division of Neurobiology, Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
- Wallenberg Center for Molecular Medicine, Linköping University, Linköping, Sweden
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12
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Bremova-Ertl T, Hofmann J, Stucki J, Vossenkaul A, Gautschi M. Inborn Errors of Metabolism with Ataxia: Current and Future Treatment Options. Cells 2023; 12:2314. [PMID: 37759536 PMCID: PMC10527548 DOI: 10.3390/cells12182314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Revised: 09/09/2023] [Accepted: 09/15/2023] [Indexed: 09/29/2023] Open
Abstract
A number of hereditary ataxias are caused by inborn errors of metabolism (IEM), most of which are highly heterogeneous in their clinical presentation. Prompt diagnosis is important because disease-specific therapies may be available. In this review, we offer a comprehensive overview of metabolic ataxias summarized by disease, highlighting novel clinical trials and emerging therapies with a particular emphasis on first-in-human gene therapies. We present disease-specific treatments if they exist and review the current evidence for symptomatic treatments of these highly heterogeneous diseases (where cerebellar ataxia is part of their phenotype) that aim to improve the disease burden and enhance quality of life. In general, a multimodal and holistic approach to the treatment of cerebellar ataxia, irrespective of etiology, is necessary to offer the best medical care. Physical therapy and speech and occupational therapy are obligatory. Genetic counseling is essential for making informed decisions about family planning.
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Affiliation(s)
- Tatiana Bremova-Ertl
- Department of Neurology, University Hospital Bern (Inselspital) and University of Bern, 3010 Bern, Switzerland; (J.H.); (J.S.)
- Center for Rare Diseases, University Hospital Bern (Inselspital) and University of Bern, 3010 Bern, Switzerland
| | - Jan Hofmann
- Department of Neurology, University Hospital Bern (Inselspital) and University of Bern, 3010 Bern, Switzerland; (J.H.); (J.S.)
| | - Janine Stucki
- Department of Neurology, University Hospital Bern (Inselspital) and University of Bern, 3010 Bern, Switzerland; (J.H.); (J.S.)
| | - Anja Vossenkaul
- Division of Pediatric Endocrinology, Diabetes and Metabolism, Department of Paediatrics, Inselspital, Bern University Hospital, University of Bern, 3010 Bern, Switzerland; (A.V.); (M.G.)
| | - Matthias Gautschi
- Division of Pediatric Endocrinology, Diabetes and Metabolism, Department of Paediatrics, Inselspital, Bern University Hospital, University of Bern, 3010 Bern, Switzerland; (A.V.); (M.G.)
- Institute of Clinical Chemistry, Inselspital, Bern University Hospital, University of Bern, 3010 Bern, Switzerland
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13
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Shakeel K, Olamendi-Portugal T, Naseem MU, Becerril B, Zamudio FZ, Delgado-Prudencio G, Possani LD, Panyi G. Of Seven New K + Channel Inhibitor Peptides of Centruroides bonito, α-KTx 2.24 Has a Picomolar Affinity for Kv1.2. Toxins (Basel) 2023; 15:506. [PMID: 37624263 PMCID: PMC10467108 DOI: 10.3390/toxins15080506] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2023] [Revised: 08/07/2023] [Accepted: 08/11/2023] [Indexed: 08/26/2023] Open
Abstract
Seven new peptides denominated CboK1 to CboK7 were isolated from the venom of the Mexican scorpion Centruroides bonito and their primary structures were determined. The molecular weights ranged between 3760.4 Da and 4357.9 Da, containing 32 to 39 amino acid residues with three putative disulfide bridges. The comparison of amino acid sequences with known potassium scorpion toxins (KTx) and phylogenetic analysis revealed that CboK1 (α-KTx 10.5) and CboK2 (α-KTx 10.6) belong to the α-KTx 10.x subfamily, whereas CboK3 (α-KTx 2.22), CboK4 (α-KTx 2.23), CboK6 (α-KTx 2.21), and CboK7 (α-KTx 2.24) bear > 95% amino acid similarity with members of the α-KTx 2.x subfamily, and CboK5 is identical to Ce3 toxin (α-KTx 2.10). Electrophysiological assays demonstrated that except CboK1, all six other peptides blocked the Kv1.2 channel with Kd values in the picomolar range (24-763 pM) and inhibited the Kv1.3 channel with comparatively less potency (Kd values between 20-171 nM). CboK3 and CboK4 inhibited less than 10% and CboK7 inhibited about 42% of Kv1.1 currents at 100 nM concentration. Among all, CboK7 showed out-standing affinity for Kv1.2 (Kd = 24 pM), as well as high selectivity over Kv1.3 (850-fold) and Kv1.1 (~6000-fold). These characteristics of CboK7 may provide a framework for developing tools to treat Kv1.2-related channelopathies.
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Affiliation(s)
- Kashmala Shakeel
- Department of Biophysics and Cell Biology, Faculty of Medicine, Research Center for Molecular Medicine, University of Debrecen, Egyetem ter. 1, 4032 Debrecen, Hungary; (K.S.); (M.U.N.)
| | - Timoteo Olamendi-Portugal
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnologia, Universidad Nacional Autónoma de México, Av. Universidad 2001, Cuernavaca 62210, Mexico; (T.O.-P.); (B.B.); (F.Z.Z.); (G.D.-P.)
| | - Muhammad Umair Naseem
- Department of Biophysics and Cell Biology, Faculty of Medicine, Research Center for Molecular Medicine, University of Debrecen, Egyetem ter. 1, 4032 Debrecen, Hungary; (K.S.); (M.U.N.)
| | - Baltazar Becerril
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnologia, Universidad Nacional Autónoma de México, Av. Universidad 2001, Cuernavaca 62210, Mexico; (T.O.-P.); (B.B.); (F.Z.Z.); (G.D.-P.)
| | - Fernando Z. Zamudio
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnologia, Universidad Nacional Autónoma de México, Av. Universidad 2001, Cuernavaca 62210, Mexico; (T.O.-P.); (B.B.); (F.Z.Z.); (G.D.-P.)
| | - Gustavo Delgado-Prudencio
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnologia, Universidad Nacional Autónoma de México, Av. Universidad 2001, Cuernavaca 62210, Mexico; (T.O.-P.); (B.B.); (F.Z.Z.); (G.D.-P.)
| | - Lourival Domingos Possani
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnologia, Universidad Nacional Autónoma de México, Av. Universidad 2001, Cuernavaca 62210, Mexico; (T.O.-P.); (B.B.); (F.Z.Z.); (G.D.-P.)
| | - Gyorgy Panyi
- Department of Biophysics and Cell Biology, Faculty of Medicine, Research Center for Molecular Medicine, University of Debrecen, Egyetem ter. 1, 4032 Debrecen, Hungary; (K.S.); (M.U.N.)
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14
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Balaram N, Jose J, Gafoor A, Balachandran S, Saritha F, Dileep KV, Balan S. Acetazolamide responsive early-onset absence epilepsy and ataxia in a toddler with a KCNA2 genetic variant; a case report. Seizure 2023; 110:157-159. [PMID: 37392502 DOI: 10.1016/j.seizure.2023.06.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Revised: 06/14/2023] [Accepted: 06/15/2023] [Indexed: 07/03/2023] Open
Affiliation(s)
- Neetha Balaram
- Department of Neurology, Government Medical College, Kozhikode, Kerala, India 673008.
| | - James Jose
- Department of Neurology, Government Medical College, Kozhikode, Kerala, India 673008
| | - Abdul Gafoor
- Department of Neurology, Government Medical College, Kozhikode, Kerala, India 673008
| | - Smita Balachandran
- Department of Neurology, Government Medical College, Kozhikode, Kerala, India 673008
| | - Francis Saritha
- Laboratory for Computational and Structural Biology, Jubilee Centre for Medical Research, Jubilee Mission Medical College and Research Institute, Thrissur, Kerala, India 680005
| | - Kalarickal Vijayan Dileep
- Laboratory for Computational and Structural Biology, Jubilee Centre for Medical Research, Jubilee Mission Medical College and Research Institute, Thrissur, Kerala, India 680005
| | - Shabeesh Balan
- Neuroscience Research Laboratory, The Center for Interdisciplinary Brain Sciences, Institute of Mental Health and Neurosciences, Kozhikode, Kerala, India 673008.
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15
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Pisani F, Spagnoli C. What are the considerations when initiating treatment for epilepsy in children? Expert Rev Neurother 2023; 23:1081-1096. [PMID: 38032395 DOI: 10.1080/14737175.2023.2288107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Accepted: 11/22/2023] [Indexed: 12/01/2023]
Abstract
INTRODUCTION There is a very wide spectrum of epilepsies and developmental and epileptic encephalopathies that affect children, from self-limited forms, not necessarily requiring treatment, to severe drug-resistant ones. AREAS COVERED In this perspective, the authors discuss the main factors to consider before drug prescription in children, considering the most recent clinical research, including age, seizure type, epilepsy syndrome, etiology, efficacy and safety profile, comorbidities, gender, available formulations, costs and drug coverage, and regulatory issues. The literature search was conducted through a PubMed search on antiseizure medications for patients aged 0-18, with respect to each of the aforementioned factors, and by checking the reference lists of relevant papers. EXPERT OPINION The most expanding field of research and innovation for clinical practice is precision medicine, which addresses the holistic treatment of genetic epilepsies and developmental and epileptic encephalopathies. It achieves this by addressing their detrimental effects on synapses, neurotransmission, and cellular signaling pathways with the double aim to treat seizures and to rescue neurodevelopmental trajectories, but also the issue of adverse events and drug resistance through pharmacogenomics.
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Affiliation(s)
- Francesco Pisani
- Human Neurosciences Department, Sapienza University of Rome, Rome, Italy
| | - Carlotta Spagnoli
- Child Neurology and Psychiatry Unit, Department of Pediatrics, Presidio Ospedaliero Santa Maria Nuova, AUSL-IRCCS di Reggio Emilia, Reggio Emilia, Italy
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16
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Freibauer AE, RamachandranNair R, Jain P, Jones KC, Whitney R. The genetic landscape of developmental and epileptic encephalopathy with spike-and-wave activation in sleep. Seizure 2023; 110:119-125. [PMID: 37352690 DOI: 10.1016/j.seizure.2023.06.017] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Revised: 06/13/2023] [Accepted: 06/19/2023] [Indexed: 06/25/2023] Open
Abstract
OBJECTIVE Epileptic Encephalopathy / Developmental Epileptic Encephalopathy with spike-and-wave activation in sleep (EE/DEE-SWAS) is defined as an epilepsy syndrome characterized by neurodevelopmental regression temporally related to the emergence of significant activation of spike-wave discharges in EEG during sleep. The availability of genetic testing has made it evident that monogenic and chromosomal abnormalities play an aetiological role in the development of EE/DEE-SWAS. We sought to review the literature to better understand the genetic landscape of EE/DEE-SWAS. METHODS In this systematic review, we reviewed cases of EE/DEE-SWAS associated with a genetic aetiology, collecting information related to the underlying aetiology, onset, management, and EEG patterns. RESULTS One hundred and seventy-two cases of EE/DEE-SWAS were identified. Genetic causes of note included pathogenic variants in GRIN2A, ZEB2, CNKSR2 and chromosome 17q21.31 deletions, each of which demonstrated unique clinical characteristics, EEG patterns, and age of onset. Factors identified to raise suspicion of a potential genetic aetiology included the presentation of DEE-SWAS and onset of SWAS under the age of five years. Treatment of EE/DEE-SWAS due to genetic causes was diverse, including a combination of anti-seizure medications, steroids, and other clinical strategies, with no clear consensus on a preferred or superior treatment. Data collected was significantly heterogeneous, with a lack of consistent use of neuropsychology testing, EEG patterns, or use of established clinical definitions. CONCLUSIONS Uniformity concerning the new definition of EE/DEE-SWAS, guidelines for management and more frequent genetic screening will be needed to guide best practices for the treatment of patients with EE/DEE-SWAS.
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Affiliation(s)
- Alexander E Freibauer
- Division of Neurology, Department of Paediatrics, McMaster University, Hamilton, ON, Canada
| | | | - Puneet Jain
- Epilepsy Program, Division of Neurology, Department of Paediatrics, Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - Kevin C Jones
- Division of Neurology, Department of Paediatrics, McMaster University, Hamilton, ON, Canada
| | - Robyn Whitney
- Division of Neurology, Department of Paediatrics, McMaster University, Hamilton, ON, Canada.
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17
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Huang H, Shakkottai VG. Targeting Ion Channels and Purkinje Neuron Intrinsic Membrane Excitability as a Therapeutic Strategy for Cerebellar Ataxia. Life (Basel) 2023; 13:1350. [PMID: 37374132 DOI: 10.3390/life13061350] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 06/03/2023] [Accepted: 06/06/2023] [Indexed: 06/29/2023] Open
Abstract
In degenerative neurological disorders such as Parkinson's disease, a convergence of widely varying insults results in a loss of dopaminergic neurons and, thus, the motor symptoms of the disease. Dopamine replacement therapy with agents such as levodopa is a mainstay of therapy. Cerebellar ataxias, a heterogeneous group of currently untreatable conditions, have not been identified to have a shared physiology that is a target of therapy. In this review, we propose that perturbations in cerebellar Purkinje neuron intrinsic membrane excitability, a result of ion channel dysregulation, is a common pathophysiologic mechanism that drives motor impairment and vulnerability to degeneration in cerebellar ataxias of widely differing genetic etiologies. We further propose that treatments aimed at restoring Purkinje neuron intrinsic membrane excitability have the potential to be a shared therapy in cerebellar ataxia akin to levodopa for Parkinson's disease.
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Affiliation(s)
- Haoran Huang
- Medical Scientist Training Program, The Ohio State University College of Medicine, Columbus, OH 43210, USA
| | - Vikram G Shakkottai
- Department of Neurology, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
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18
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Koch NA, Sonnenberg L, Hedrich UBS, Lauxmann S, Benda J. Loss or gain of function? Effects of ion channel mutations on neuronal firing depend on the neuron type. Front Neurol 2023; 14:1194811. [PMID: 37292138 PMCID: PMC10244640 DOI: 10.3389/fneur.2023.1194811] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Accepted: 05/03/2023] [Indexed: 06/10/2023] Open
Abstract
Introduction Clinically relevant mutations to voltage-gated ion channels, called channelopathies, alter ion channel function, properties of ionic currents, and neuronal firing. The effects of ion channel mutations are routinely assessed and characterized as loss of function (LOF) or gain of function (GOF) at the level of ionic currents. However, emerging personalized medicine approaches based on LOF/GOF characterization have limited therapeutic success. Potential reasons are among others that the translation from this binary characterization to neuronal firing is currently not well-understood-especially when considering different neuronal cell types. In this study, we investigate the impact of neuronal cell type on the firing outcome of ion channel mutations. Methods To this end, we simulated a diverse collection of single-compartment, conductance-based neuron models that differed in their composition of ionic currents. We systematically analyzed the effects of changes in ion current properties on firing in different neuronal types. Additionally, we simulated the effects of known mutations in KCNA1 gene encoding the KV1.1 potassium channel subtype associated with episodic ataxia type 1 (EA1). Results These simulations revealed that the outcome of a given change in ion channel properties on neuronal excitability depends on neuron type, i.e., the properties and expression levels of the unaffected ionic currents. Discussion Consequently, neuron-type specific effects are vital to a full understanding of the effects of channelopathies on neuronal excitability and are an important step toward improving the efficacy and precision of personalized medicine approaches.
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Affiliation(s)
- Nils A. Koch
- Institute of Neurobiology, Faculty of Mathematics and Natural Sciences, University of Tübingen, Tübingen, Germany
- Bernstein Center for Computational Neuroscience Tübingen, Tübingen, Germany
| | - Lukas Sonnenberg
- Institute of Neurobiology, Faculty of Mathematics and Natural Sciences, University of Tübingen, Tübingen, Germany
- Bernstein Center for Computational Neuroscience Tübingen, Tübingen, Germany
| | - Ulrike B. S. Hedrich
- Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Stephan Lauxmann
- Institute of Neurobiology, Faculty of Mathematics and Natural Sciences, University of Tübingen, Tübingen, Germany
- Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Jan Benda
- Institute of Neurobiology, Faculty of Mathematics and Natural Sciences, University of Tübingen, Tübingen, Germany
- Bernstein Center for Computational Neuroscience Tübingen, Tübingen, Germany
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19
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Paulhus K, Glasscock E. Novel Genetic Variants Expand the Functional, Molecular, and Pathological Diversity of KCNA1 Channelopathy. Int J Mol Sci 2023; 24:8826. [PMID: 37240170 PMCID: PMC10219020 DOI: 10.3390/ijms24108826] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Revised: 05/11/2023] [Accepted: 05/13/2023] [Indexed: 05/28/2023] Open
Abstract
The KCNA1 gene encodes Kv1.1 voltage-gated potassium channel α subunits, which are crucial for maintaining healthy neuronal firing and preventing hyperexcitability. Mutations in the KCNA1 gene can cause several neurological diseases and symptoms, such as episodic ataxia type 1 (EA1) and epilepsy, which may occur alone or in combination, making it challenging to establish simple genotype-phenotype correlations. Previous analyses of human KCNA1 variants have shown that epilepsy-linked mutations tend to cluster in regions critical for the channel's pore, whereas EA1-associated mutations are evenly distributed across the length of the protein. In this review, we examine 17 recently discovered pathogenic or likely pathogenic KCNA1 variants to gain new insights into the molecular genetic basis of KCNA1 channelopathy. We provide the first systematic breakdown of disease rates for KCNA1 variants in different protein domains, uncovering potential location biases that influence genotype-phenotype correlations. Our examination of the new mutations strengthens the proposed link between the pore region and epilepsy and reveals new connections between epilepsy-related variants, genetic modifiers, and respiratory dysfunction. Additionally, the new variants include the first two gain-of-function mutations ever discovered for KCNA1, the first frameshift mutation, and the first mutations located in the cytoplasmic N-terminal domain, broadening the functional and molecular scope of KCNA1 channelopathy. Moreover, the recently identified variants highlight emerging links between KCNA1 and musculoskeletal abnormalities and nystagmus, conditions not typically associated with KCNA1. These findings improve our understanding of KCNA1 channelopathy and promise to enhance personalized diagnosis and treatment for individuals with KCNA1-linked disorders.
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Affiliation(s)
| | - Edward Glasscock
- Department of Biological Sciences, Southern Methodist University, Dallas, TX 75275, USA;
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20
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Qin C, Yang X, Zhang Y, Deng G, Huang X, Zuo Z, Sun F, Cao Z, Chen Z, Wu Y. Functional Characterization of a New Degradation Peptide BmTX4-P1 from Traditional Chinese Scorpion Medicinal Material. Toxins (Basel) 2023; 15:toxins15050340. [PMID: 37235373 DOI: 10.3390/toxins15050340] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Revised: 04/28/2023] [Accepted: 04/29/2023] [Indexed: 05/28/2023] Open
Abstract
Thermally processed Buthus martensii Karsch scorpion is an important traditional Chinese medical material that has been widely used to treat various diseases in China for over one thousand years. Our recent work showed that thermally processed Buthus martensii Karsch scorpions contain many degraded peptides; however, the pharmacological activities of these peptides remain to be studied. Here, a new degraded peptide, BmTX4-P1, was identified from processed Buthus martensii Karsch scorpions. Compared with the venom-derived wild-type toxin peptide BmTX4, BmTX4-P1 missed some amino acids at the N-terminal and C-terminal regions, while containing six conserved cysteine residues, which could be used to form disulfide bond-stabilized α-helical and β-sheet motifs. Two methods (chemical synthesis and recombinant expression) were used to obtain the BmTX4-P1 peptide, named sBmTX4-P1 and rBmTX4-P1. Electrophysiological experimental results showed that sBmTX4-P1 and rBmTX4-P1 exhibited similar activities to inhibit the currents of hKv1.2 and hKv1.3 channels. In addition, the experimental electrophysiological results of recombinant mutant peptides of BmTX4-P1 indicated that the two residues of BmTX4-P1 (Lys22 and Tyr31) were the key residues for its potassium channel inhibitory activity. In addition to identifying a new degraded peptide, BmTX4-P1, from traditional Chinese scorpion medicinal material with high inhibitory activities against the hKv1.2 and hKv1.3 channels, this study also provided a useful method to obtain the detailed degraded peptides from processed Buthus martensii Karsch scorpions. Thus, the study laid a solid foundation for further research on the medicinal function of these degraded peptides.
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Affiliation(s)
- Chenhu Qin
- College of Life Sciences, Wuhan University, Wuhan 430072, China
- Department of Biochemistry and Molecular Biology, College of Basic Medicine, Hubei University of Medicine, Shiyan 442000, China
| | - Xuhua Yang
- College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Yuanyuan Zhang
- College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Gang Deng
- College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Xin Huang
- College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Zheng Zuo
- College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Fang Sun
- College of Life Sciences, Wuhan University, Wuhan 430072, China
- Department of Biochemistry and Molecular Biology, College of Basic Medicine, Hubei University of Medicine, Shiyan 442000, China
| | - Zhijian Cao
- College of Life Sciences, Wuhan University, Wuhan 430072, China
- Center for BioDrug Research, Wuhan University, Wuhan 430072, China
| | - Zongyun Chen
- College of Life Sciences, Wuhan University, Wuhan 430072, China
- Department of Biochemistry and Molecular Biology, College of Basic Medicine, Hubei University of Medicine, Shiyan 442000, China
| | - Yingliang Wu
- College of Life Sciences, Wuhan University, Wuhan 430072, China
- Center for BioDrug Research, Wuhan University, Wuhan 430072, China
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21
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The emergence of genotypic divergence and future precision medicine applications. HANDBOOK OF CLINICAL NEUROLOGY 2023; 192:87-99. [PMID: 36796950 DOI: 10.1016/b978-0-323-85538-9.00013-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
Genotypic divergence is a term adapted from population genetics and intimately linked to evolution. We use divergence here to emphasize the differences that set individuals apart in any cohort. The history of genetics is filled with descriptions of genotypic differences, but causal inference of interindividual biological variation has been scarce. We suggest that the practice of precision medicine requires a divergent approach, an approach dependent on the causal interpretation of previous convergent (and preliminary) knowledge in the field. This knowledge has relied on convergent descriptive syndromology (lumping), which has overemphasized a reductionistic gene determinism on the quest of seeking associations without causal understanding. Regulatory variants with small effect and somatic mutations are some of the modifying factors that lead to incomplete penetrance and intrafamilial variable expressivity often observed in apparently monogenic clinical disorders. A truly divergent approach to precision medicine requires splitting, that is, the consideration of different layers of genetic phenomena that interact causally in a nonlinear fashion. This chapter reviews convergences and divergences in genetics and genomics, aiming to discuss what can be causally understood to approximate the as-yet utopian lands of Precision Medicine for patients with neurodegenerative disorders.
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22
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Müller P, Takacs DS, Hedrich UBS, Coorg R, Masters L, Glinton KE, Dai H, Cokley JA, Riviello JJ, Lerche H, Cooper EC. KCNA1 gain-of-function epileptic encephalopathy treated with 4-aminopyridine. Ann Clin Transl Neurol 2023; 10:656-663. [PMID: 36793218 PMCID: PMC10109319 DOI: 10.1002/acn3.51742] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Accepted: 01/31/2023] [Indexed: 02/17/2023] Open
Abstract
Precision medicine for Mendelian epilepsy is rapidly developing. We describe an early infant with severely pharmacoresistant multifocal epilepsy. Exome sequencing revealed the de novo variant p.(Leu296Phe) in the gene KCNA1, encoding the voltage-gated K+ channel subunit KV 1.1. So far, loss-of-function variants in KCNA1 have been associated with episodic ataxia type 1 or epilepsy. Functional studies of the mutated subunit in oocytes revealed a gain-of-function caused by a hyperpolarizing shift of voltage dependence. Leu296Phe channels are sensitive to block by 4-aminopyridine. Clinical use of 4-aminopyridine was associated with reduced seizure burden, enabled simplification of co-medication and prevented rehospitalization.
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Affiliation(s)
- Peter Müller
- Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tuebingen, Tuebingen, 72076, Germany
| | - Danielle S Takacs
- Division of Neurology and Developmental Neuroscience, Epilepsy and Neurophysiology, Department of Pediatrics, Texas Children's Hospital, Baylor College of Medicine, Houston, Texas, USA.,Department of Neurology, Baylor College of Medicine, Houston, Texas, USA
| | - Ulrike B S Hedrich
- Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tuebingen, Tuebingen, 72076, Germany
| | - Rohini Coorg
- Division of Neurology and Developmental Neuroscience, Epilepsy and Neurophysiology, Department of Pediatrics, Texas Children's Hospital, Baylor College of Medicine, Houston, Texas, USA.,Department of Neurology, Baylor College of Medicine, Houston, Texas, USA
| | - Laura Masters
- Division of Neurology and Developmental Neuroscience, Epilepsy and Neurophysiology, Department of Pediatrics, Texas Children's Hospital, Baylor College of Medicine, Houston, Texas, USA.,Department of Neurology, Baylor College of Medicine, Houston, Texas, USA
| | - Kevin E Glinton
- Division of Genetics, Department of Pediatrics, Texas Children's Hospital, Baylor College of Medicine, Houston, Texas, USA.,Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Hongzheng Dai
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA.,Baylor Genetics, Houston, Texas, USA
| | - Jon A Cokley
- Division of Neurology and Developmental Neuroscience, Epilepsy and Neurophysiology, Department of Pediatrics, Texas Children's Hospital, Baylor College of Medicine, Houston, Texas, USA
| | - James J Riviello
- Division of Neurology and Developmental Neuroscience, Epilepsy and Neurophysiology, Department of Pediatrics, Texas Children's Hospital, Baylor College of Medicine, Houston, Texas, USA.,Department of Neurology, Baylor College of Medicine, Houston, Texas, USA
| | - Holger Lerche
- Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tuebingen, Tuebingen, 72076, Germany
| | - Edward C Cooper
- Department of Neurology, Baylor College of Medicine, Houston, Texas, USA.,Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA.,Department of Neuroscience, Baylor College of Medicine, Houston, Texas, USA
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23
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Müller P, Lerche H. [Gene Therapy for Epilepsy: Clinical Studies are on the Road]. FORTSCHRITTE DER NEUROLOGIE-PSYCHIATRIE 2023; 91:135-140. [PMID: 36716773 DOI: 10.1055/a-1995-5405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
For more than 10 years, research has been conducted on gene therapies for the most severe forms of epilepsy, which until now have proven resistant to treatment. First gene therapies are now in clinical trials for pharmacoresistant focal epilepsies and Dravet syndrome. In this article, we describe how these and many more gene therapies work and what they target.
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Affiliation(s)
- Peter Müller
- Abteilung Neurologie mit Schwerpunkt Epileptologie, Hertie Institute für klinische Hirnforschung, Universität Tübingen
| | - Holger Lerche
- Abteilung Neurologie mit Schwerpunkt Epileptologie, Hertie Institute für klinische Hirnforschung, Universität Tübingen
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24
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Mroczek M, Iyadurai S. Neuromuscular and Neuromuscular Junction Manifestations of the PURA-NDD: A Systematic Review of the Reported Symptoms and Potential Treatment Options. Int J Mol Sci 2023; 24:ijms24032260. [PMID: 36768582 PMCID: PMC9917016 DOI: 10.3390/ijms24032260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 01/14/2023] [Accepted: 01/20/2023] [Indexed: 01/26/2023] Open
Abstract
PURA-related neurodevelopmental disorders (PURA-NDDs) are a rare genetic disease caused by pathogenic autosomal dominant variants in the PURA gene or a deletion encompassing the PURA gene. PURA-NDD is clinically characterized by neurodevelopmental delay, learning disability, neonatal hypotonia, feeding difficulties, abnormal movements, and epilepsy. It is generally considered to be central nervous system disorders, with generalized weakness, associated hypotonia, cognitive and development deficits in early development, and seizures in late stages. Although it is classified predominantly as a central nervous syndrome disorder, some phenotypic features, such as myopathic facies, respiratory insufficiency of muscle origin, and myopathic features on muscle biopsy and electrodiagnostic evaluation, point to a peripheral (neuromuscular) source of weakness. Patients with PURA-NDD have been increasingly identified in exome-sequenced cohorts of patients with neuromuscular- and congenital myasthenic syndrome-like phenotypes. Recently, fluctuating weakness noted in a PURA-NDD patient, accompanied by repetitive nerve stimulation abnormalities, suggested the disease to be a channelopathy and, more specifically, a neuromuscular junction disorder. Treatment with pyridostigmine or salbutamol led to clinical improvement of neuromuscular function in two reported cases. The goal of this systematic retrospective review is to highlight the motor symptoms of PURA-NDD, to further describe the neuromuscular phenotype, and to emphasize the role of potential treatment opportunities of the neuromuscular phenotype in the setting of the potential role of PURA protein in the neuromuscular junction and the muscles.
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Affiliation(s)
- Magdalena Mroczek
- Center for Cardiovascular Genetics & Gene Diagnostics, Foundation for People with Rare Diseases, 8952 Schlieren, Switzerland
- Correspondence: (M.M.); (S.I.)
| | - Stanley Iyadurai
- Division of Neurology, Johns Hopkins All Children’s Hospital, 501 6th Ave S, St. Petersburg, FL 33701, USA
- Correspondence: (M.M.); (S.I.)
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25
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Naseem MU, Gurrola-Briones G, Romero-Imbachi MR, Borrego J, Carcamo-Noriega E, Beltrán-Vidal J, Zamudio FZ, Shakeel K, Possani LD, Panyi G. Characterization and Chemical Synthesis of Cm39 (α-KTx 4.8): A Scorpion Toxin That Inhibits Voltage-Gated K + Channel K V1.2 and Small- and Intermediate-Conductance Ca 2+-Activated K + Channels K Ca2.2 and K Ca3.1. Toxins (Basel) 2023; 15:41. [PMID: 36668861 PMCID: PMC9866218 DOI: 10.3390/toxins15010041] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 12/22/2022] [Accepted: 12/27/2022] [Indexed: 01/06/2023] Open
Abstract
A novel peptide, Cm39, was identified in the venom of the scorpion Centruroides margaritatus. Its primary structure was determined. It consists of 37 amino acid residues with a MW of 3980.2 Da. The full chemical synthesis and proper folding of Cm39 was obtained. Based on amino acid sequence alignment with different K+ channel inhibitor scorpion toxin (KTx) families and phylogenetic analysis, Cm39 belongs to the α-KTx 4 family and was registered with the systematic number of α-KTx 4.8. Synthetic Cm39 inhibits the voltage-gated K+ channel hKV1.2 with high affinity (Kd = 65 nM). The conductance-voltage relationship of KV1.2 was not altered in the presence of Cm39, and the analysis of the toxin binding kinetics was consistent with a bimolecular interaction between the peptide and the channel; therefore, the pore blocking mechanism is proposed for the toxin-channel interaction. Cm39 also inhibits the Ca2+-activated KCa2.2 and KCa3.1 channels, with Kd = 502 nM, and Kd = 58 nM, respectively. However, the peptide does not inhibit hKV1.1, hKV1.3, hKV1.4, hKV1.5, hKV1.6, hKV11.1, mKCa1.1 K+ channels or the hNaV1.5 and hNaV1.4 Na+ channels at 1 μM concentrations. Understanding the unusual selectivity profile of Cm39 motivates further experiments to reveal novel interactions with the vestibule of toxin-sensitive channels.
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Affiliation(s)
- Muhammad Umair Naseem
- Department of Biophysics and Cell Biology, Faculty of Medicine, Research Center for Molecular Medicine, University of Debrecen, Egyetem ter. 1, 4032 Debrecen, Hungary
| | - Georgina Gurrola-Briones
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnologia, Universidad Nacional Autónoma de México, Av. Universidad 2001, Cuernavaca 62210, Morelos, Mexico
| | - Margarita R. Romero-Imbachi
- Grupo de Investigaciones Herpetológicas y Toxinológicas, Centro de Investigaciones Biomédicas, Departamento de Biología, Facultad de Ciencias Naturales, Exactas y de la Educación, Universidad del Cauca, Sector Tulcan, Calle 2 N 3N-100, Popayán 190002, Cauca, Colombia
| | - Jesus Borrego
- Department of Biophysics and Cell Biology, Faculty of Medicine, Research Center for Molecular Medicine, University of Debrecen, Egyetem ter. 1, 4032 Debrecen, Hungary
| | - Edson Carcamo-Noriega
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnologia, Universidad Nacional Autónoma de México, Av. Universidad 2001, Cuernavaca 62210, Morelos, Mexico
| | - José Beltrán-Vidal
- Grupo de Investigaciones Herpetológicas y Toxinológicas, Centro de Investigaciones Biomédicas, Departamento de Biología, Facultad de Ciencias Naturales, Exactas y de la Educación, Universidad del Cauca, Sector Tulcan, Calle 2 N 3N-100, Popayán 190002, Cauca, Colombia
| | - Fernando Z. Zamudio
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnologia, Universidad Nacional Autónoma de México, Av. Universidad 2001, Cuernavaca 62210, Morelos, Mexico
| | - Kashmala Shakeel
- Department of Biophysics and Cell Biology, Faculty of Medicine, Research Center for Molecular Medicine, University of Debrecen, Egyetem ter. 1, 4032 Debrecen, Hungary
| | - Lourival Domingos Possani
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnologia, Universidad Nacional Autónoma de México, Av. Universidad 2001, Cuernavaca 62210, Morelos, Mexico
| | - Gyorgy Panyi
- Department of Biophysics and Cell Biology, Faculty of Medicine, Research Center for Molecular Medicine, University of Debrecen, Egyetem ter. 1, 4032 Debrecen, Hungary
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26
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Mechanism of 4-aminopyridine inhibition of the lysosomal channel TMEM175. Proc Natl Acad Sci U S A 2022; 119:e2208882119. [PMID: 36279431 PMCID: PMC9636928 DOI: 10.1073/pnas.2208882119] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Transmembrane protein 175 (TMEM175) is an evolutionarily distinct lysosomal cation channel whose mutation is associated with the development of Parkinson’s disease. Here, we present a cryoelectron microscopy structure and molecular simulations of TMEM175 bound to 4-aminopyridine (4-AP), the only known small-molecule inhibitor of TMEM175 and a broad K
+
channel inhibitor, as well as a drug approved by the Food and Drug Administration against multiple sclerosis. The structure shows that 4-AP, whose mode of action had not been previously visualized, binds near the center of the ion conduction pathway, in the open state of the channel. Molecular dynamics simulations reveal that this binding site is near the middle of the transmembrane potential gradient, providing a rationale for the voltage-dependent dissociation of 4-AP from TMEM175. Interestingly, bound 4-AP rapidly switches between three predominant binding poses, stabilized by alternate interaction patterns dictated by the twofold symmetry of the channel. Despite this highly dynamic binding mode, bound 4-AP prevents not only ion permeation but also water flow. Together, these studies provide a framework for the rational design of novel small-molecule inhibitors of TMEM175 that might reveal the role of this channel in human lysosomal physiology both in health and disease.
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27
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Krey I, Platzer K, Esterhuizen A, Berkovic SF, Helbig I, Hildebrand MS, Lerche H, Lowenstein D, Møller RS, Poduri A, Sadleir L, Sisodiya SM, Weckhuysen S, Wilmshurst JM, Weber Y, Lemke JR. Current practice in diagnostic genetic testing of the epilepsies. Epileptic Disord 2022; 24:765-786. [PMID: 35830287 PMCID: PMC10752379 DOI: 10.1684/epd.2022.1448] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Accepted: 05/10/2022] [Indexed: 01/19/2023]
Abstract
Epilepsy genetics is a rapidly developing field, in which novel disease-associated genes, novel mechanisms associated with epilepsy, and precision medicine approaches are continuously being identified. In the past decade, advances in genomic knowledge and analysis platforms have begun to make clinical genetic testing accessible for, in principle, people of all ages with epilepsy. For this reason, the Genetics Commission of the International League Against Epilepsy (ILAE) presents this update on clinical genetic testing practice, including current techniques, indications, yield of genetic testing, recommendations for pre- and post-test counseling, and follow-up after genetic testing is completed. We acknowledge that the resources vary across different settings but highlight that genetic diagnostic testing for epilepsy should be prioritized when the likelihood of an informative finding is high. Results of genetic testing, in particular the identification of causative genetic variants, are likely to improve individual care. We emphasize the importance of genetic testing for individuals with epilepsy as we enter the era of precision therapy.
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Affiliation(s)
- Ilona Krey
- Institute of Human Genetics, University of Leipzig Medical Center, Leipzig, Germany
| | - Konrad Platzer
- Institute of Human Genetics, University of Leipzig Medical Center, Leipzig, Germany
| | - Alina Esterhuizen
- Division of Human Genetics, Department of Pathology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
- National Health Laboratory Service, Groote Schuur Hospital, Cape Town, South Africa
| | - Samuel F. Berkovic
- Epilepsy Research Centre, Department of Medicine, University of Melbourne (Austin Health), Heidelberg, VIC, Australia
| | - Ingo Helbig
- Institute of Clinical Molecular Biology, Christian-Albrechts-University of Kiel, Kiel, Germany
- Department of Neuropediatrics, University Medical Center Schleswig-Holstein, Christian-Albrechts-University, Building C, Arnold-Heller-Straße 3, 24105 Kiel, Germany
- Division of Neurology, Children’s Hospital of Philadelphia, Philadelphia, 3401 Civic Center Blvd, Philadelphia, PA 19104, USA
- The Epilepsy NeuroGenetics Initiative (ENGIN), Children’s Hospital of Philadelphia, Philadelphia, 3401 Civic Center Blvd, Philadelphia, PA 19104, USA
- Department of Biomedical and Health Informatics (DBHi), Children’s Hospital of Philadelphia, Philadelphia, PA, 19104 USA
- Department of Neurology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, 19104 USA
| | - Michael S. Hildebrand
- Epilepsy Research Centre, Department of Medicine, The University of Melbourne, Austin Health, Heidelberg and Murdoch Children’s Research Institute, Royal Children’s Hospital, Victoria, Australia
| | - Holger Lerche
- Department of Epileptology and Neurology, Hertie Institute for Clinical Brain Research, University of Tübingen, Germany
| | - Daniel Lowenstein
- Department of Neurology, University of California, San Francisco, USA
| | - Rikke S. Møller
- Department of Epilepsy Genetics and Personalized Medicine, Danish Epilepsy Centre, Dianalund, Denmark
- Institute for Regional Health Services, University of Southern Denmark, Odense, Denmark
| | - Annapurna Poduri
- Epilepsy Genetics Program, Department of Neurology, Boston Children’s Hospital, Harvard Medical School, Boston, MA, USA
| | - Lynette Sadleir
- Department of Paediatrics and Child Health, University of Otago, Wellington, New Zealand
| | - Sanjay M. Sisodiya
- Department of Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology London, UK and Chalfont Centre for Epilepsy, Buckinghamshire, UK
| | - Sarah Weckhuysen
- Center for Molecular Neurology, VIB-University of Antwerp, VIB, Antwerp, Belgium; Department of Neurology, University Hospital Antwerp, Antwerp, Belgium
| | - Jo M. Wilmshurst
- Department of Paediatric Neurology, Paediatric and Child Health, Red Cross War Memorial Children’s Hospital, Neuroscience Institute, University of Cape Town, South Africa
| | - Yvonne Weber
- Department of Epileptology and Neurology, Hertie Institute for Clinical Brain Research, University of Tübingen, Germany
- Department of Epileptology and Neurology, University of Aachen, Germany
| | - Johannes R. Lemke
- Institute of Human Genetics, University of Leipzig Medical Center, Leipzig, Germany
- Center for Rare Diseases, University of Leipzig Medical Center, Leipzig, Germany
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28
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Knowles JK, Helbig I, Metcalf CS, Lubbers LS, Isom LL, Demarest S, Goldberg EM, George AL, Lerche H, Weckhuysen S, Whittemore V, Berkovic SF, Lowenstein DH. Precision medicine for genetic epilepsy on the horizon: Recent advances, present challenges, and suggestions for continued progress. Epilepsia 2022; 63:2461-2475. [PMID: 35716052 PMCID: PMC9561034 DOI: 10.1111/epi.17332] [Citation(s) in RCA: 36] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 06/14/2022] [Accepted: 06/14/2022] [Indexed: 01/18/2023]
Abstract
The genetic basis of many epilepsies is increasingly understood, giving rise to the possibility of precision treatments tailored to specific genetic etiologies. Despite this, current medical therapy for most epilepsies remains imprecise, aimed primarily at empirical seizure reduction rather than targeting specific disease processes. Intellectual and technological leaps in diagnosis over the past 10 years have not yet translated to routine changes in clinical practice. However, the epilepsy community is poised to make impressive gains in precision therapy, with continued innovation in gene discovery, diagnostic ability, and bioinformatics; increased access to genetic testing and counseling; fuller understanding of natural histories; agility and rigor in preclinical research, including strategic use of emerging model systems; and engagement of an evolving group of stakeholders (including patient advocates, governmental resources, and clinicians and scientists in academia and industry). In each of these areas, we highlight notable examples of recent progress, new or persistent challenges, and future directions. The future of precision medicine for genetic epilepsy looks bright if key opportunities on the horizon can be pursued with strategic and coordinated effort.
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Affiliation(s)
- Juliet K. Knowles
- Department of Neurology, Division of Child Neurology, Stanford University School of Medicine, Stanford, California, USA
| | - Ingo Helbig
- Division of Neurology, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
- Epilepsy NeuroGenetics Initiative, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
- Department of Biomedical and Health Informatics, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
- Department of Neurology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, Pennsylvania, USA
- Institute of Clinical Molecular Biology, University of Kiel, Kiel, Germany
- Department of Neuropediatrics, University Medical Center Schleswig-Holstein, Kiel, Germany
| | - Cameron S. Metcalf
- Department of Pharmacology and Toxicology, College of Pharmacy, University of Utah, Salt Lake City, Utah, USA
| | - Laura S. Lubbers
- Citizens United for Research in Epilepsy, Chicago, Illinois, USA
| | - Lori L. Isom
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Scott Demarest
- Department of Pediatrics and Neurology, University of Colorado, School of Medicine, Aurora, Colorado, USA
| | - Ethan M. Goldberg
- Division of Neurology, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
- Epilepsy NeuroGenetics Initiative, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
- Department of Neurology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, Pennsylvania, USA
| | - Alfred L. George
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Holger Lerche
- Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Sarah Weckhuysen
- Division of Neurology, University Hospital Antwerp, Antwerp, Belgium
- Applied and Translational Neurogenomics Group, Vlaams Instituut voor Biotechnologie Center for Molecular Neurology, Antwerp, Belgium
- Translational Neurosciences, Faculty of Medicine and Health Science, University of Antwerp, Antwerp, Belgium
- μNEURO Research Center of Excellence, University of Antwerp, Antwerp, Belgium
| | - Vicky Whittemore
- Division of Neuroscience, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Rockville, Maryland, USA
| | - Samuel F. Berkovic
- Epilepsy Research Centre, Department of Medicine, Austin Health, University of Melbourne, Melbourne, Victoria, Australia
| | - Daniel H. Lowenstein
- Department of Neurology, University of California, San Francisco, San Francisco, California, USA
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29
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Bayat A, Fenger CD, Techlo TR, Højte AF, Nørgaard I, Hansen TF, Rubboli G, Møller RS, Group DCCRS. Impact of Genetic Testing on Therapeutic Decision-Making in Childhood-Onset Epilepsies-a Study in a Tertiary Epilepsy Center. Neurotherapeutics 2022; 19:1353-1367. [PMID: 35723786 PMCID: PMC9587146 DOI: 10.1007/s13311-022-01264-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/08/2022] [Indexed: 12/13/2022] Open
Abstract
We assessed the frequency of pediatric monogenic epilepsies and precision therapies at a tertiary epilepsy center. We analyzed medical records of children, born in 2006-2011 and followed at the Danish Epilepsy Center from January to December 2015; 357 patients were identified, of whom 27 without epilepsy and 35 with acquired brain damage were excluded. Of the remaining 295 children, 188 were consented for study inclusion and genetic testing. At inclusion, 86/188 had a preexisting genetic diagnosis and did not undergo further genetic testing. The 102 genetically unsolved patients underwent WES, which identified a (likely) pathogenic variant in eight patients and a highly relevant variant of unknown significance (VUS) in seven additional patients. Single nucleotide polymorphism array was performed in the remaining 87 patients and revealed no (likely) pathogenic copy number variants (CNVs). Patients with a genetic diagnosis had a significantly lower median age at seizure onset and more often had febrile seizures, status epilepticus, or neurodevelopmental impairment compared to those who remained genetically unsolved. Most common epilepsies were focal or multifocal epilepsies and developmental and epileptic encephalopathies (DDEs). Fifty-three patients, with a putative genetic diagnosis, were potentially eligible for precision therapy approaches. Indeed, genetic diagnosis enabled treatment adjustment in 32/53 (60%); 30/32 (93%) patients experienced at least a 50% reduction in seizure burden while only 4/32 (12.5%) became seizure-free. In summary, a genetic diagnosis was achieved in approximately 50% of patients with non-acquired epilepsy enabling precision therapy approaches in half of the patients, a strategy that results in > 50% reduction in seizure burden, in the majority of the treated patients.
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Affiliation(s)
- Allan Bayat
- Department of Epilepsy Genetics and Personalized Medicine, Danish Epilepsy Center, Filadelfia, Dianalund, Denmark.
- Department of Regional Health Research, University of Southern Denmark, Odense, Denmark.
| | - Christina D Fenger
- Department of Epilepsy Genetics and Personalized Medicine, Danish Epilepsy Center, Filadelfia, Dianalund, Denmark
- Amplexa Genetics A/S, Odense, Denmark
| | - Tanya R Techlo
- Department of Neurology, Danish Headache Center, Copenhagen University Hospital, Glostrup, Denmark
| | - Anne F Højte
- Department of Epilepsy Genetics and Personalized Medicine, Danish Epilepsy Center, Filadelfia, Dianalund, Denmark
| | | | - Thomas F Hansen
- Department of Neurology, Danish Headache Center, Copenhagen University Hospital, Glostrup, Denmark
- Novo Nordic Foundation Center for Protein Research, Copenhagen University, Copenhagen, Denmark
| | - Guido Rubboli
- Department of Epilepsy Genetics and Personalized Medicine, Danish Epilepsy Center, Filadelfia, Dianalund, Denmark
- Copenhagen University, Copenhagen, Denmark
| | - Rikke S Møller
- Department of Epilepsy Genetics and Personalized Medicine, Danish Epilepsy Center, Filadelfia, Dianalund, Denmark
- Department of Regional Health Research, University of Southern Denmark, Odense, Denmark
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30
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Boßelmann CM, Hedrich UB, Müller P, Sonnenberg L, Parthasarathy S, Helbig I, Lerche H, Pfeifer N. Predicting the functional effects of voltage-gated potassium channel missense variants with multi-task learning. EBioMedicine 2022; 81:104115. [PMID: 35759918 PMCID: PMC9250003 DOI: 10.1016/j.ebiom.2022.104115] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 05/30/2022] [Accepted: 05/31/2022] [Indexed: 01/18/2023] Open
Abstract
BACKGROUND Variants in genes encoding voltage-gated potassium channels are associated with a broad spectrum of neurological diseases including epilepsy, ataxia, and intellectual disability. Knowledge of the resulting functional changes, characterized as overall ion channel gain- or loss-of-function, is essential to guide clinical management including precision medicine therapies. However, for an increasing number of variants, little to no experimental data is available. New tools are needed to evaluate variant functional effects. METHODS We catalogued a comprehensive dataset of 959 functional experiments across 19 voltage-gated potassium channels, leveraging data from 782 unique disease-associated and synthetic variants. We used these data to train a taxonomy-based multi-task learning support vector machine (MTL-SVM), and compared performance to several baseline methods. FINDINGS MTL-SVM maintains channel family structure during model training, improving overall predictive performance (mean balanced accuracy 0·718 ± 0·041, AU-ROC 0·761 ± 0·063) over baseline (mean balanced accuracy 0·620 ± 0·045, AU-ROC 0·711 ± 0·022). We can obtain meaningful predictions even for channels with few known variants (KCNC1, KCNQ5). INTERPRETATION Our model enables functional variant prediction for voltage-gated potassium channels. It may assist in tailoring current and future precision therapies for the increasing number of patients with ion channel disorders. FUNDING This work was supported by intramural funding of the Medical Faculty, University of Tuebingen (PATE F.1315137.1), the Federal Ministry for Education and Research (Treat-ION, 01GM1907A/B/G/H) and the German Research Foundation (FOR-2715, Le1030/16-2, He8155/1-2).
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Affiliation(s)
- Christian Malte Boßelmann
- Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tuebingen, Hoppe-Seyler-Str. 3, D-72076 Tuebingen, Germany,Methods in Medical Informatics, Department of Computer Science, University of Tuebingen, Sand 14, D-72076 Tuebingen, Germany
| | - Ulrike B.S. Hedrich
- Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tuebingen, Hoppe-Seyler-Str. 3, D-72076 Tuebingen, Germany
| | - Peter Müller
- Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tuebingen, Hoppe-Seyler-Str. 3, D-72076 Tuebingen, Germany
| | - Lukas Sonnenberg
- Institute for Neurobiology, University of Tuebingen, Tuebingen, Germany
| | - Shridhar Parthasarathy
- Division of Neurology, Children's Hospital of Philadelphia, Philadelphia, PA, USA,The Epilepsy NeuroGenetics Initiative (ENGIN), Children's Hospital of Philadelphia, Philadelphia, PA, USA,Department of Biomedical and Health Informatics (DBHi), Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Ingo Helbig
- Division of Neurology, Children's Hospital of Philadelphia, Philadelphia, PA, USA,The Epilepsy NeuroGenetics Initiative (ENGIN), Children's Hospital of Philadelphia, Philadelphia, PA, USA,Department of Biomedical and Health Informatics (DBHi), Children's Hospital of Philadelphia, Philadelphia, PA, USA,Department of Neurology, University of Pennsylvania, Philadelphia, PA, USA
| | - Holger Lerche
- Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tuebingen, Hoppe-Seyler-Str. 3, D-72076 Tuebingen, Germany,Corresponding authors.
| | - Nico Pfeifer
- Methods in Medical Informatics, Department of Computer Science, University of Tuebingen, Sand 14, D-72076 Tuebingen, Germany,Interfaculty Institute for Biomedical Informatics (IBMI), University of Tuebingen, Tuebingen, Germany,Faculty of Medicine, University of Tuebingen, Tuebingen, Germany,German Center for Infection Research, Partner Site Tuebingen, Tuebingen, Germany,Corresponding authors.
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31
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Radomski KL, Zi X, Lischka FW, Noble MD, Galdzicki Z, Armstrong RC. Acute axon damage and demyelination are mitigated by 4-aminopyridine (4-AP) therapy after experimental traumatic brain injury. Acta Neuropathol Commun 2022; 10:67. [PMID: 35501931 PMCID: PMC9059462 DOI: 10.1186/s40478-022-01366-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Accepted: 04/11/2022] [Indexed: 11/10/2022] Open
Abstract
Damage to long axons in white matter tracts is a major pathology in closed head traumatic brain injury (TBI). Acute TBI treatments are needed that protect against axon damage and promote recovery of axon function to prevent long term symptoms and neurodegeneration. Our prior characterization of axon damage and demyelination after TBI led us to examine repurposing of 4-aminopyridine (4-AP), an FDA-approved inhibitor of voltage-gated potassium (Kv) channels. 4-AP is currently indicated to provide symptomatic relief for patients with chronic stage multiple sclerosis, which involves axon damage and demyelination. We tested clinically relevant dosage of 4-AP as an acute treatment for experimental TBI and found multiple benefits in corpus callosum axons. This randomized, controlled pre-clinical study focused on the first week after TBI, when axons are particularly vulnerable. 4-AP treatment initiated one day post-injury dramatically reduced axon damage detected by intra-axonal fluorescence accumulations in Thy1-YFP mice of both sexes. Detailed electron microscopy in C57BL/6 mice showed that 4-AP reduced pathological features of mitochondrial swelling, cytoskeletal disruption, and demyelination at 7 days post-injury. Furthermore, 4-AP improved the molecular organization of axon nodal regions by restoring disrupted paranode domains and reducing Kv1.2 channel dispersion. 4-AP treatment did not resolve deficits in action potential conduction across the corpus callosum, based on ex vivo electrophysiological recordings at 7 days post-TBI. Thus, this first study of 4-AP effects on axon damage in the acute period demonstrates a significant decrease in multiple pathological hallmarks of axon damage after experimental TBI.
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Affiliation(s)
- Kryslaine L. Radomski
- Department of Anatomy, Physiology and Genetics, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814 USA
- Center for Neuroscience and Regenerative Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814 USA
| | - Xiaomei Zi
- Department of Anatomy, Physiology and Genetics, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814 USA
- Center for Neuroscience and Regenerative Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814 USA
| | - Fritz W. Lischka
- Department of Anatomy, Physiology and Genetics, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814 USA
- Biomedical Instrumentation Center, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814 USA
| | - Mark D. Noble
- Department of Biomedical Genetics, School of Medicine and Dentistry, University of Rochester, 601 Elmwood Ave, Box 633, Rochester, NY 14642 USA
| | - Zygmunt Galdzicki
- Department of Anatomy, Physiology and Genetics, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814 USA
- Center for Neuroscience and Regenerative Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814 USA
| | - Regina C. Armstrong
- Department of Anatomy, Physiology and Genetics, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814 USA
- Center for Neuroscience and Regenerative Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814 USA
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32
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Backwell L, Marsh JA. Diverse Molecular Mechanisms Underlying Pathogenic Protein Mutations: Beyond the Loss-of-Function Paradigm. Annu Rev Genomics Hum Genet 2022; 23:475-498. [PMID: 35395171 DOI: 10.1146/annurev-genom-111221-103208] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Most known disease-causing mutations occur in protein-coding regions of DNA. While some of these involve a loss of protein function (e.g., through premature stop codons or missense changes that destabilize protein folding), many act via alternative molecular mechanisms and have dominant-negative or gain-of-function effects. In nearly all cases, these non-loss-of-function mutations can be understood by considering interactions of the wild-type and mutant protein with other molecules, such as proteins, nucleic acids, or small ligands and substrates. Here, we review the diverse molecular mechanisms by which pathogenic mutations can have non-loss-of-function effects, including by disrupting interactions, increasing binding affinity, changing binding specificity, causing assembly-mediated dominant-negative and dominant-positive effects, creating novel interactions, and promoting aggregation and phase separation. We believe that increased awareness of these diverse molecular disease mechanisms will lead to improved diagnosis (and ultimately treatment) of human genetic disorders. Expected final online publication date for the Annual Review of Genomics and Human Genetics, Volume 23 is October 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Lisa Backwell
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Edinburgh, United Kingdom;
| | - Joseph A Marsh
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Edinburgh, United Kingdom;
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Beltrán-Corbellini Á, Aledo-Serrano Á, Møller RS, Pérez-Palma E, García-Morales I, Toledano R, Gil-Nagel A. Epilepsy Genetics and Precision Medicine in Adults: A New Landscape for Developmental and Epileptic Encephalopathies. Front Neurol 2022; 13:777115. [PMID: 35250806 PMCID: PMC8891166 DOI: 10.3389/fneur.2022.777115] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Accepted: 01/27/2022] [Indexed: 12/14/2022] Open
Abstract
This review aims to provide an updated perspective of epilepsy genetics and precision medicine in adult patients, with special focus on developmental and epileptic encephalopathies (DEEs), covering relevant and controversial issues, such as defining candidates for genetic testing, which genetic tests to request and how to interpret them. A literature review was conducted, including findings in the discussion and recommendations. DEEs are wide and phenotypically heterogeneous electroclinical syndromes. They generally have a pediatric presentation, but patients frequently reach adulthood still undiagnosed. Identifying the etiology is essential, because there lies the key for precision medicine. Phenotypes modify according to age, and although deep phenotyping has allowed to outline certain entities, genotype-phenotype correlations are still poor, commonly leading to long-lasting diagnostic odysseys and ineffective therapies. Recent adult series show that the target patients to be identified for genetic testing are those with epilepsy and different risk factors. The clinician should take active part in the assessment of the pathogenicity of the variants detected, especially concerning variants of uncertain significance. An accurate diagnosis implies precision medicine, meaning genetic counseling, prognosis, possible future therapies, and a reduction of iatrogeny. Up to date, there are a few tens of gene mutations with additional concrete treatments, including those with restrictive/substitutive therapies, those with therapies modifying signaling pathways, and channelopathies, that are worth to be assessed in adults. Further research is needed regarding phenotyping of adult syndromes, early diagnosis, and the development of targeted therapies.
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Affiliation(s)
| | - Ángel Aledo-Serrano
- Epilepsy Program, Neurology Department, Hospital Ruber Internacional, Madrid, Spain
- *Correspondence: Ángel Aledo-Serrano
| | - Rikke S. Møller
- Department of Epilepsy Genetics and Personalized Treatment, The Danish Epilepsy Centre, Dianalund, Denmark
| | - Eduardo Pérez-Palma
- Universidad del Desarrollo, Centro de Genética y Genómica, Facultad de Medicina Clínica Alemana, Santiago, Chile
| | - Irene García-Morales
- Epilepsy Program, Neurology Department, Hospital Ruber Internacional, Madrid, Spain
- Epilepsy Unit, Neurology Department, Clínico San Carlos University Hospital, Madrid, Spain
| | - Rafael Toledano
- Epilepsy Program, Neurology Department, Hospital Ruber Internacional, Madrid, Spain
- Epilepsy Unit, Neurology Department, Ramón y Cajal University Hospital, Madrid, Spain
| | - Antonio Gil-Nagel
- Epilepsy Program, Neurology Department, Hospital Ruber Internacional, Madrid, Spain
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Zimmern V, Minassian B, Korff C. A Review of Targeted Therapies for Monogenic Epilepsy Syndromes. Front Neurol 2022; 13:829116. [PMID: 35250833 PMCID: PMC8891748 DOI: 10.3389/fneur.2022.829116] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2021] [Accepted: 01/13/2022] [Indexed: 11/15/2022] Open
Abstract
Genetic sequencing technologies have led to an increase in the identification and characterization of monogenic epilepsy syndromes. This increase has, in turn, generated strong interest in developing “precision therapies” based on the unique molecular genetics of a given monogenic epilepsy syndrome. These therapies include diets, vitamins, cell-signaling regulators, ion channel modulators, repurposed medications, molecular chaperones, and gene therapies. In this review, we evaluate these therapies from the perspective of their clinical validity and discuss the future of these therapies for individual syndromes.
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Affiliation(s)
- Vincent Zimmern
- Division of Child Neurology, University of Texas Southwestern, Dallas, TX, United States
- *Correspondence: Vincent Zimmern
| | - Berge Minassian
- Division of Child Neurology, University of Texas Southwestern, Dallas, TX, United States
| | - Christian Korff
- Pediatric Neurology Unit, University Hospitals, Geneva, Switzerland
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35
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Miceli F, Guerrini R, Nappi M, Soldovieri MV, Cellini E, Gurnett CA, Parmeggiani L, Mei D, Taglialatela M. Distinct epilepsy phenotypes and response to drugs in KCNA1 gain- and loss-of function variants. Epilepsia 2021; 63:e7-e14. [PMID: 34778950 PMCID: PMC9299230 DOI: 10.1111/epi.17118] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Revised: 10/01/2021] [Accepted: 10/22/2021] [Indexed: 11/29/2022]
Abstract
A wide phenotypic spectrum of neurological diseases is associated with KCNA1 (Kv1.1) variants. To investigate the molecular basis of such a heterogeneous clinical presentation and identify the possible correlation with in vitro phenotypes, we compared the functional consequences of three heterozygous de novo variants (p.P403S, p.P405L, and p.P405S) in Kv1.1 pore region found in four patients with severe developmental and epileptic encephalopathy (DEE), with those of a de novo variant in the voltage sensor (p.A261T) identified in two patients with mild, carbamazepine-responsive, focal epilepsy. Patch-clamp electrophysiology was used to investigate the functional properties of mutant Kv1.1 subunits, both expressed as homomers and heteromers with wild-type Kv1.1 subunits. KCNA1 pore mutations markedly decreased (p. P405S) or fully suppressed (p. P403S, p. P405L) Kv1.1-mediated currents, exerting loss-of-function (LoF) effects. By contrast, channels carrying the p.A261T variant exhibited a hyperpolarizing shift of the activation process, consistent with a gain-of-function (GoF) effect. The present results unveil a novel correlation between in vitro phenotype (GoF vs LoF) and clinical course (mild vs severe) in KCNA1-related phenotypes. The excellent clinical response to carbamazepine observed in the patients carrying the A261T variant suggests an exquisite sensitivity of KCNA1 GoF to sodium channel inhibition that should be further explored.
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Affiliation(s)
- Francesco Miceli
- Department of Neuroscience, University of Naples "Federico II", Naples, Italy
| | - Renzo Guerrini
- Neuroscience Department, A. Meyer Children's Hospital, University of Florence, Florence, Italy
| | - Mario Nappi
- Department of Neuroscience, University of Naples "Federico II", Naples, Italy
| | | | - Elena Cellini
- Neuroscience Department, A. Meyer Children's Hospital, University of Florence, Florence, Italy
| | - Christina A Gurnett
- Department of Neurology, Washington University in St. Louis, St. Louis, Missouri, USA
| | | | - Davide Mei
- Neuroscience Department, A. Meyer Children's Hospital, University of Florence, Florence, Italy
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A Novel KCNA2 Variant in a Patient with Non-Progressive Congenital Ataxia and Epilepsy: Functional Characterization and Sensitivity to 4-Aminopyridine. Int J Mol Sci 2021; 22:ijms22189913. [PMID: 34576077 PMCID: PMC8469797 DOI: 10.3390/ijms22189913] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 09/02/2021] [Accepted: 09/08/2021] [Indexed: 12/26/2022] Open
Abstract
Kv1.2 channels, encoded by the KCNA2 gene, are localized in the central and peripheral nervous system, where they regulate neuronal excitability. Recently, heterozygous mutations in KCNA2 have been associated with a spectrum of symptoms extending from epileptic encephalopathy, intellectual disability, and cerebellar ataxia. Patients are treated with a combination of antiepileptic drugs and 4-aminopyridine (4-AP) has been recently trialed in specific cases. We identified a novel variant in KCNA2, E236K, in a Serbian proband with non-progressive congenital ataxia and early onset epilepsy, treated with sodium valproate. To ascertain the pathogenicity of E236K mutation and to verify its sensitivity to 4-AP, we transfected HEK 293 cells with Kv1.2 WT or E236K cDNAs and recorded potassium currents through the whole-cell patch-clamp. In silico analysis supported the electrophysiological data. E236K channels showed voltage-dependent activation shifted towards negative potentials and slower kinetics of deactivation and activation compared with Kv1.2 WT. Heteromeric Kv1.2 WT+E236K channels, resembling the condition of the heterozygous patient, confirmed a mixed gain- and loss-of-function (GoF/LoF) biophysical phenotype. 4-AP inhibited both Kv1.2 and E236K channels with similar potency. Homology modeling studies of mutant channels suggested a reduced interaction between the residue K236 in the S2 segment and the gating charges at S4. Overall, the biophysical phenotype of E236K channels correlates with the mild end of the clinical spectrum reported in patients with GoF/LoF defects. The response to 4-AP corroborates existing evidence that KCNA2-disorders could benefit from variant-tailored therapeutic approaches, based on functional studies.
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